Dynamic igbt gate drive to reduce switching loss

Abstract

An inverter includes an N-channel IGBT, with a freewheeling diode, coupled to a phase of an electric machine, and has a MOSFET coupling a local voltage with a gate of the IGBT and configured to transition from saturation to linear operation as a current flow direction through the diode switches from positive to negative while the IGBT initiates a current through the electric machine.

What is claimed is: 
     
         1 . A vehicle comprising:
 an inverter including an N-channel IGBT, with a freewheeling diode, coupled to a phase of an electric machine, and having a MOSFET coupling a local voltage with a gate of the IGBT and configured to transition from saturation to linear operation as a current flow direction through the diode switches from positive to negative while the IGBT initiates a current through the electric machine.   
     
     
         2 . The vehicle of  claim 1  further including a gate resistor coupled between the gate of the IGBT and the MOSFET. 
     
     
         3 . The vehicle of  claim 2 , wherein the resistance of the resistor is selected to limit a drain current of the MOSFET to a predetermined threshold for an associated gate voltage of the IGBT. 
     
     
         4 . The vehicle of  claim 1 , wherein the MOSFET is a P-channel MOSFET. 
     
     
         5 . The vehicle of  claim 1  further including a charge pump circuit to output a MOSFET gate voltage greater than the local voltage to turn-on the MOSFET, and wherein the MOSFET is an N-channel MOSFET. 
     
     
         6 . A vehicle DC-DC converter comprising:
 an inductor;   an N-channel charge IGBT with a freewheeling diode coupled between a terminal of the inductor and a local ground; and   a charge MOSFET coupling a local voltage with a gate of the charge IGBT, and configured to transition from saturation to linear operation as a current flow direction in the diode switches from positive to negative while the IGBT initiates a current through the inductor.   
     
     
         7 . The converter of  claim 6  further including a N-channel pass IGBT having a freewheeling pass diode coupled between the terminal of the inductor and an output terminal, and a pass MOSFET coupling a local pass voltage with a pass gate of the pass IGBT, wherein the MOSFET is configured to transition from saturation to linear operation as a direction of current flow in the pass diode switches from positive to negative while the pass IGBT initiates an output current through an electric machine coupled with the output terminal. 
     
     
         8 . The vehicle of  claim 7 , wherein the current is based on inductance of a phase of the electric machine, a bus voltage, and a rotational speed of the electric machine. 
     
     
         9 . A power electronics module for a vehicle comprising:
 an N-channel IGBT having an emitter, gate, and collector;   a freewheeling diode coupled parallel with the IGBT; and   a MOSFET coupling a local voltage with the IGBT gate and configured to transition from saturation to linear operation as a direction of current flowing through the diode reverses from positive to negative while the IGBT turns on.   
     
     
         10 . The vehicle of  claim 9  further including a gate resistor coupled between the gate of the IGBT and the MOSFET. 
     
     
         11 . The vehicle of  claim 10 , wherein the resistance of the resistor is selected to limit a drain current of the MOSFET to a predetermined threshold for an associated gate voltage of the IGBT. 
     
     
         12 . The vehicle of  claim 9 , wherein the MOSFET is a P-channel MOSFET. 
     
     
         13 . The vehicle of  claim 9  further including a charge pump circuit to output a MOSFET gate voltage greater than the local voltage to turn-on the MOSFET, and wherein the MOSFET is an N-channel MOSFET.